The invention relates to a connecting rod for a toggle-joint device allowing a first component to be held stably in one of two positions relative to a second component.
A toggle-joint device such as this comprises a trigger articulated to the first component about a first axis, the aforementioned connecting rod being articulated, on the one hand, to the second component about a second axis parallel to the first axis and, on the other hand, to the trigger about a third axis parallel to the other two. When the trigger is in a stable position, the third axis lies outside the plane of the first two axes, and the switch from one stable position to the other requires the third axis to cross the plane of the first two axes, with deformation of the connecting rod. Thrusting means combined with elastic means are also provided to cause the trigger to change position abruptly.
The connecting rod in such a device, while being of a small size by comparison with the other components, constitutes a significant element on which the correct operation of the toggle-joint mechanism and its durability over time depend.
A toggle-joint device such as this may be used in diverse applications requiring two components to switch from one stable position to another stable position relative to one another abruptly. For example, the device may be used to control the change in positions of the valves in a differential hydraulic motor. Such a toggle-joint device may also be used for other applications, particularly in the field of circuit breakers or electric switches that require an abrupt change in position of two electric contacts, or in other locking mechanisms.
The object of the invention, is above all, to provide a connecting rod that makes it possible to simplify the production of a toggle-joint device and to ensure that it operates correctly.
According to the invention, the connecting rod has an essentially U-shaped central part, the transverse lower branch of which is designed to form the third axis of articulation of the trigger, this lower branch connecting more or less at right angles to lateral branches capable of elastic deformation, these lateral branches continuing at their upper end in the form of segments bent outward and parallel to the transverse branch, these segments having elasticity in torsion about their geometric axis so as to exert a rotational return force on the lateral branches about this geometric axis which is coincident with the second axis.
The connecting rod according to the invention thus elastically returns the trigger to a stable position.
As a preference, the lateral branches have an arched shape; advantageously, these lateral branches form bows lying in a plane orthogonal to the transverse branch.
The outwardly bent segments may be continued by other segments bent in the opposite direction to the bows; as a preference, these other segments are bent at right angles, are orthogonal to the transverse branch and are parallel to one another.
The ends of these segments may be set into the second component, and the freedom of the connecting rod to rotate about the second axis is provided by the torsional elasticity of the segments directed along the second axis.
Also as a preference, the connecting rod is made with longitudinal fibers of high mechanical strength capable of providing the lateral branches of the connecting rod with tensile and compressive elasticity, these longitudinal fibers being embedded in a plastic matrix capable of providing the segments that extend along the second axis with torsional elasticity.
The longitudinal fibers may be glass fibers or carbon fibers.
The invention also relates to a toggle-joint device comprising a connecting rod as defined previously.